RITM-200 Reactor
MAJOR TECHNICAL PARAMETERS
Parameter Value
Technology developer, country of origin
JSC “Afrikantov OKBM”,
40S. While integral reactor configuration virtually eliminates large loss-of-coolant accident (LOCA), the other inherent features and active and passive safety systems form diversity, redundancy, physical separation, and functional independence to achieve the required safety level and reliability.
Nuclear Steam Supply System
RITM nuclear steam supply system consists of the reactor core, four steam generators (SGs) integrated in the reactor pressure vessel, four canned main circulation pumps, and two pressurizers. The primary cooling system is based on forced circulation during normal operation and allows natural circulation for emergency condition.
Reactor Core
RITM reactor core accommodates low enriched fuel assemblies similar to KLT-40S that ensures long time operation without refueling and meets international non-proliferation requirements. The height of the core is 1650 mm. The core consists of 199 fuel assemblies with uranium-intensive cermet fuel. The core has the service life of 8 TWh. The fuel rods are resistant to power changes with a design rate of 0.1% Prated/s.
Reactivity Control
A group of control rods drive mechanisms is intended to compensate for the excessive reactivity at start up, power operation and reactor trip. A group of safety rods is designed to scram the reactor and to maintain it in subcritical condition. The design of control and safety rods is based on the drives used in KLT-40S.
Reactor Coolant System
The RPV is a thick-walled cylindrical pressure vessel with an integrally welded bottom head and a removable top head. The integral RPV has four main circulation pumps located in separate external hydraulic chambers with side horizontal sockets for SG cassette nozzles. The pumps are single-stage vaned and have a canned asynchronous electric motor. The SGs provide steam of 295°C at 3.82 MPa and capacity of 261 t/h.
Steam Generator
The RITM-200 uses once-through (straight tube) SGs. The SG is divided into four primary circuit loops. Each loop consists of three once-through cassettes (12 in total) with a common feed water and common steam manifolds. Each cassette consists of 7 modules. There is a specially designed system for SG leakage detection.
In case a leak is detected, it is possible to find out and isolate the leaking module individually.
Pressurizer
The design adopts pressure compensation gas system well-proven in the Russian ship power engineering. It is characterized by a simple design, which increases reliability, compactness, and requires no electric power. The compensation system is divided into two independent parts to reduce the pipe diameter in the compensatory nozzles of the steam generating unit and to decrease a coolant leakage rate in large break LOCA. It is possible to use one of pressurizers as hydraulic accumulator, increasing reactor plant reliability in case of LOCA.
4. Safety Features
RITM-200 applies the defense-in-depth safety principle combined with inherent features and passive systems.
Inherent safety features are applied to control power density and reactor scram, limit primary coolant pressure and temperature, heating rate, primary circuit depressurization rate, fuel damage scope, and maintain reactor vessel integrity in severe accidents. RITM-200 optimally combines passive and active safety systems to cope with abnormal operating occurrences and design basis accidents. Pressurizer is divided into two independent ones to minimize size of potential coolant leakage rate.
Engineered Safety System Approach and Configuration
The high safety level of RITM series reactors is achieved by inherent safety features and a combination of passive and active safety systems. Redundancy of safety system equipment and channels and their functional and/or physical separation are provided to ensure high reliability. In case of automated systems failure, self- actuating devices will actuate directly under the primary circuit pressure to ensure reactor trip and initiate the safety systems. Safety rods drop into the core by gravity with spring assist when power is removed from electromagnetic couplings consequently ensure reactor scram even in case of total station blackout.
Residual Heat Removal System
The residual heat removal system (RHRS) consists of four safety trains:
- Active safety loop with forced circulation through steam generator.
- Active safety loop with forced circulation through the heat exchanger of primary-third circuits of primary circuit coolant purification loop.
- Two passive safety loops with natural circulation from water tanks through SGs. All safety train are connected to different SGs and provide residual heat removal in compliance with single failure criterion.
Emergency Core Cooling System
The emergency core cooling system consists of safety injection system (SIS) for water injection in primary circuit to mitigate the consequences of a break loss-of-coolant accident. The system is based on active and
passive principles with redundancy of active elements in each channel and consists of:
- Two passive pressurized hydraulic accumulators;
- Two active channels with water tanks and two make-up pumps in each channel.
In combination with the residual heat removal system the passive safety trains anticipate a post-accident grace period of 72 hours without operator action or power in case of combination of LOCA and total station blackout.
Containment System
The containment consists of three levels:
- Primary containment designed for internal pressure of 0.5 MPa (abs) with dimensions of 6 m × 6 m × 15.5 m around the reactor vessel to localize possible radioactive releases (~300 m3 of free space).
- Secondary containment is a solid building core made of thick reinforced concrete walls (800 mm thick) to protect primary containment from external impact.
- Third level of containment is a collapsible building structure of thin reinforced concrete walls to dissipate most of the energy of external impact and minimize influence on secondary containment.
The design of solid core and collapsible structures takes into consideration the maximum potential external impacts including large commercial aircraft crash.
5. Instrumentation and Control Systems
An automated control system is provided in the RITM-200 based nuclear power plant to monitor and control plant processes. This system possesses necessary redundancy with regard to safety function fulfilment and allows both automated and remote control of the power plant.
6. Plant Layout Arrangement
The land-based small NPP consists of two RITM-200 reactors with a specified electrical capacity of 100 MW.
Buildings are arranged to optimize interconnections and interfaces between buildings and to minimize unused areas. An aerial view of small NPP and the plant layout are presented below.
RITM-200 plant layout
Small NPP layout is sectioned in two areas:
- Secured area related to power generation systems itself, including reactor and turbine buildings and cooling towers. It also includes the building for nuclear material management (radwaste building).
Auxiliary system area consists of water treatment buildings, fire station, administration building, etc.
Small NPP secured area. Small NPP auxiliary area.
Small NPP site segmentation allows utilizing modular approach for simplification of possible future plant electrical capacity growth. Construction of additional areas with reactor and turbine buildings allows increasing power generation incrementally by step of 100 MW. While the auxiliary building systems stay in shared use for all nuclear units.Small NPP site area for 100 MW is 14.8 acres (59 894 m2), 200 MW - 22.2 acres (89 840 m2), and 300 MW - 29.7 acres (120 192 m2).
Scalability of small NPP based on RITM-200 rectors.
Main building
The optimized design of small NPP consists of one reactor building with two RITM-200 reactors. It is assumed that the two reactors will be commissioned simultaneously. The main building actually consists of three buildings:
- Reactor building footprint is 45 m x 44 m and 35 m of height.
- Turbine building footprint is 30 m x 63 m and 31 m of height.
- Nuclear material management building (radwaste building) footprint is 36 m x 48 m and 19 m of height.
7. Design and Licensing Status
The RITM-200 design is developed in conformity with Russian law, codes and standards for nuclear power plants and safety principles developed by the world community and IAEA requirements.
8. Development Milestones
2012 Detailed design of RITM-200 2018 Land-based NPP conceptual design
2023 Site license
2024 License for construction, first concrete 2027 License for operation, NPP commissioning
MAJOR TECHNICAL PARAMETERS
Parameter Value
Technology developer, country of origin
NIKIET,Russian Federation
Reactor type PWR
Coolant/moderator High purity water Thermal/electrical capacity,
MW(t)/MW(e)
30 / 6.6
Primary circulation Natural circulation NSSS Operating Pressure
(primary/secondary), MPa
16.5 Core Inlet/Outlet Coolant
Temperature (oC)
249 / 330
Fuel type/assembly array UO2 particles in a metallic silumin or zirconium matrix, metal-ceramic/ 54-55 Number of fuel assemblies in
the core
265 Fuel enrichment (%) 19.75 Core Discharge Burnup
(GWd/ton)
1.15 Refuelling Cycle (months) 200
Reactivity control mechanism Soluble boron and control rod insertion Approach to safety systems Hybrid (passive + active) system
Design life (years) 30
Plant footprint (m2) ~10 000 RPV height/diameter (m) 9.8 / 2.9 RPV weight (metric ton) 32
Seismic Design (SSE) VIII-IX-MSK 64 Fuel cycle requirements /
Approach
Traditional
Distinguishing features Autonomous passive reactor decay removal system; guard vessel; iron- water biological shielding; and the biological shielding tanks
Design status Conceptual design
1. Introduction
The UNITHERM is a small transportable nuclear power plant (NPP) with a capacity of 30 MW(t) and a rated electrical output of 6.6 MW developed based upon NIKIET’s experience in designing marine nuclear installations. The UNITHERM reactor is intended for electricity supply to urban areas and industrial enterprises in remote regions. UNITHERM adopts a natural circulated primary cooling system and is intended for minimal operational staffing with an option for unattended operation and a centralized regional support facilities monitoring. The UNITHERM design adopts proven technology and operational experience of the WWER type reactors. The design aims for fabrication, assembly and commissioning of the NPP modules to be carried out at factory. The UNITHERM reactor is designed to operate for 20-25 years without refuelling as both a land-based and barge mounted NPP. NPP with UNITHERM may consist of a number of units depending on the purpose and demand of costumers need.
2. Target Application
The UNITHERM NPP can be used as a source of energy for the generation of electricity, district heating, seawater desalination and process steam production. In general, the configuration and design of the UNITHERM is sufficiently flexible to be adjusted or modified for different target functions and user requirements, without compromising the underlying principles of the design.